Gel Synthesis of Hexaferrites Pb1-xLaxFe12-xZnxO19 and Properties of Multiferroic Composite Ceramics PZT-Pb1-xLaxFe12-xZnxO19.

Inna V Lisnevskaya,Inga A Aleksandrova

doi:10.3390/nano10091630

Inna V Lisnevskaya, Inga A Aleksandrova

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https://doi.org/10.3390/nano10091630

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Journal: Nanomaterials	Publication Date: Aug 19, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: Southern Federal University

Abstract

We investigated the opportunities for obtaining hexaferrites Pb1−xLaxFe12−xZnxO19 (x = 0–1) from citrate–glycerin gel and showed that synthesis occurs via the formation of the Fe3O4 phase; products with a small amount of hematite impurity Fe2O3 can be obtained after firing at 800 to 900 °C with 0 ≤ x ≤ 0.5. If x > 0.5, perovskite-like LaFeO3 is formed in samples, so that if x = 0.9–1, the synthesis products virtually do not contain phases with hexaferrite structures and represent a mixture of LaFeO3, Fe2O3, and Fe3O4. Within the range of 0 ≤ x ≤ 0.5, the electrical and magnetic characteristics of hexaferrites Pb1−xLaxFe12−xZnxO19 are slightly dependent on x and have the following average values: A relative permittivity ε/ε0 ~ 45, a dielectric loss tangent tan δ ~ 0.6, an electrical resistivity R ~ 109 Ohm cm, coercivity Hc ~ 3 kOe, saturation magnetization Ms ~ 50 emu/g, and remanent magnetization Mr ~ 25 emu/g. The magnetoelectric (ME) ceramics 50 wt.% PZTNB-1 + 50 wt.% Pb1−xLaxFe12−xZnxO19 (PZTNB-1 is an industrial piezoelectric material based on lead titanate zirconate (PZT) do not contain impurity phases and have the following characteristics: Piezoelectric coefficients d33 = 10–60 and −d31 = 2–30 pC/N, piezoelectric voltage coefficients g33 = 2–13 and −g31 = 1–5 mV m/N, an electromechanical coupling coefficient Kp = 0.03–0.13, magnetic parameters Hc = 3–1 kOe, Ms = 50–30, and Mr = 25–12 emu/g. The maximum ME coupling coefficient ΔE/ΔH ~ 1.75 mV/(cm Oe) was achieved with x = 0.5.

Highlights

Ferrites with a structure of magnetoplumbite MFe12O19 are long- and well-known [1,2,3]
The aim of this study was to investigate the possibilities of obtaining solid solutions based on lead hexaferrite Pb1−xLaxFe12−xZnxO19 using the gel method, as well as obtaining and studying the properties of magnetoelectric (ME) composites 50 wt.% PZTNB-1 + 50 wt.% Pb1−xLaxFe12−xZnxO19, where piezoelectric material based on lead titanate zirconate (PZT) of the PZTNB-1 industrial brand is used as a piezoelectric component
To study the electrophysical and magnetic properties of Pb1−xLaxFe12−xZnxO19 solid solutions, xerogels were calcined at 800 ◦C for 3 h; after that, ceramic samples were sintered from the obtained ferrite powders at a temperature of 1000 ◦C for 2 h, from which discs with a height of 1 mm were made for further measurements

Summary

Introduction

Ferrites with a structure of magnetoplumbite MFe12O19 (where M = Ba, Sr, Pb, and other large doubly charged cations) are long- and well-known [1,2,3]. They are magnetically hard materials with high coercivity, high saturation magnetization, and large magnetic anisotropy. Like the structure of other hexaferrites with a magnetoplumbite structure, it can be described as a combination of spinel and hexagonal blocks In this case, oxygen anions, together with large lead ions, are densely packed with an alternation sequence of 10 ABABACBCBC layers along the c axis, where the third and eighth layers contain Pb2+ cations.

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